The electromagnetic spectrum is a scarce resource and due to a rapidly increasing number and variety of devices that communicate wirelessly it is in significant demand. Consequently, portions of useful spectrum are allocated to specific uses to try to ensure reliable operation of wireless devices. Uses of electromagnetic spectrum include mobile telecommunications, terrestrial and satellite television (TV), WIFI, radio and wireless microphones etc. Due to a scarcity of spectrum, frequency allocations often change. Furthermore frequency gaps or guard bands between frequency bands allocated to systems which transmit and receive within those frequency bands for different uses can decrease which can thereby increase in-band and out-of-band interference. A change in frequency allocations and decreasing guard bands can lead existing devices to experience increased interference and may in some examples result in the devices being unable to receive signals for which they were designed.
Terrestrial TV broadcasts have traditionally been allocated a significant portion of frequency spectrum. However, as demand for spectrum increases and alternative methods for receiving TV content gain in popularity, there is a drive from other spectrum users to utilise portions of the spectrum which have traditionally been allocated to terrestrial TV. Additionally, in for example the UK and across the EU, a switch from analogue to digital terrestrial TV has led to spectrum traditionally allocated to terrestrial TV being freed up for use by mobile telecommunications, particularly for example 3GPP Long Term Evolution (LTE). These factors have led to mobile telecommunications signals being transmitted in close proximity in the frequency domain to terrestrial TV signals and being transmitted over frequencies previously allocated to terrestrial TV. Furthermore, due to extra revenue that mobile telecommunications can provide and increasing capacity required, frequencies allocated to mobile communications may further encroach into or close to frequencies which have been previously allocated to terrestrial TV. Furthermore this allocation may change dynamically. Consequently TV receivers will be required to receive terrestrial TV signals when locations of the TV signals in the frequency domain are close to frequency bands in which signals for other uses are transmitted.